CREATE PROCEDURE ee(ingreso text)
BEGIN
DECLARE tamanio tinyint;
DECLARE comas tinyint;
DECLARE elemento text;
SET tamanio = LENGTH(ingreso);
SET comas = instr(ingreso,',');
while comas > 0 do
SET elemento = SUBSTRING(ingreso,1,comas-1);
SET ingreso = SUBSTRING(ingreso,comas+1);
SELECT elemento;
SET comas = instr(ingreso,',');
END while;
END //
 

CALL ee('e,a,d,g');//
+----------+
| elemento |
+----------+
| e        | 
+----------+
1 ROW IN SET (0.00 sec)
 
+----------+
| elemento |
+----------+
| a        | 
+----------+
1 ROW IN SET (0.00 sec)
 
+----------+
| elemento |
+----------+
| d        | 
+----------+
1 ROW IN SET (0.00 sec)
 
Query OK, 0 ROWS affected (0.00 sec)